Steatopygia

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Steatopygia is a high degree of fat accumulation in and around the buttocks. The deposit of fat is not confined to the gluteal regions, but extends to the outside and front of the thighs, forming a thick layer reaching sometimes to the knee.

Khoikhoi woman exhibiting steatopygia.

This development constitutes a genetic characteristic of the Khoisan. It is specially a feature of the women, but it occurs in a lesser degree in the males (in most genetic variations of Homo sapiens, females tend to exhibit a greater propensity to adipose tissue accumulation in the buttock region as compared with males). It has also been noted among the Pygmies of Central Africa. Among the Khoisan, it is regarded as a sign of beauty: it begins in infancy and is fully developed by the time of the first pregnancy. It is often accompanied by the formation known as elongated labia (labia minora that may extend as much as 4 inches outside the vulva).

Khoikhoi woman and man (drawing of 1900)

Steatopygia would seem to have been a characteristic of a population which once extended from the Gulf of Aden to the Cape of Good Hope, of which stock Khoisan and Pygmies are remnants. While the Khoisan afford the most noticeable examples of its development, it is by no means rare in other parts of Africa, and occurs even more frequently among Basters of the male sex than among Khoikhoi women. It is also observed among females of Andamanese Negritos.

What seems certain is that steatopygia in both sexes was fairly widespread among early human populations. The discovery in the caves of the south of France of figures in ivory presenting a remarkable development of the thighs, and even the peculiar prolongation of the nymphae, has been used to support this theory^{[citation needed]}. However, the type of Neolithic Venus figurines sometimes referred to as "steatopygian Venus" do not strictly qualify as steatopygian, since they exhibit an angle of approximately 120 degrees between the back and the buttocks, while steatopygia strictly speaking is diagnosed at an angle of about 90 degrees only (Passemard 1938).

Steatopygia is an adaptive physiological trait for female humans living in hot environments, as it allows them to maximise their bodies' surface-area/volume ratio while maintaining enough fat to produce hormones needed for menstruation.^{[citation needed]} Longer, leaner bodies are more adaptive, according to Allen's rule, because there is a greater surface area through which heat can radiate, thereby maintaining homeostasis.^{[citation needed]} With fat deposited heavily in only certain areas in the middle on the trunk of the body, the limbs are left skinny enough to radiate heat more efficiently.^{[citation needed]} Being able to store large amounts of fat is important in very seasonal environments like those of South Africa, where even now foragers have little to eat during the dry season, and live largely off of their stored fat.^{[citation needed]} Women who have this fat can continue to reproduce through the unproductive seasons, thereby increasing their fitness.^{[citation needed]}